Prior to the present invention, various methods and mechanisms have been utilized to improve the precision stamping of parts so that there is better fit of the stamped parts to provide high quality assemblies made from a plurality of stamped parts. For example, special guide pins have been used to accurately guide upper and lower dies moved in a press between open and closed positions so that a part will be accurately stamped by the dies. Furthermore, gages have been utilized within the dies to stabilize the blank or part being struck so that the stamped part will meet requirements. Also parts have been stamped in preliminary runs in press lines, and subsequently, gaged to ascertain that the stamped parts meets specifications. If such parts do not meet specifications, appropriate adjustments are made in the dies and other critical press line components until the stamped parts meet with approval. Such procedures, while satisfactory, are time consuming and costly and generally do not meet requirements for high quality and quantity output.
In many respects, improved stampings have been obtained by the "Multiple Stamping Dies With Cumulative Stamping Markers and Methods Of Stamping Parts" of application Ser. No. 358,508, (Chrysler docket No. 941634), now U.S. Pat. No. 5,471,923, assigned to the assignee of this invention and hereby incorporated by reference. In that application, a multiple station stamping press line is disclosed with die sets having special bottoming markers which imprint bench marks on the part at each stamping station to provide a readout on the finally stamped part that reveals the accuracy of stamping at each station and identifies any station that is not stamping to specifications.
While repeatable stampings of high quality have been provided using the markers and methods of the above identified application, assemblies of parts coming from different press lines often did not properly match with one another to meet higher standards needed for quality and quantity production. To achieve such goals, the present invention provides for the serial marking of the parts being stamped along different press lines with bench marks that interrelate with one another. With the parts having bench marking that relate to one another regardless of the press line that produces the part, the parts can, by using the bench marks, be accurately positioned relative to each other and held until secured into a permanent assembly with optimized accuracy.
It is a feature, object and advantage of this invention to provide new and improved press line stamping procedures in plural press lines of multiple stamping stations. Preferably, each station is equipped with a die set with bottoming markers that apply bench marks to the parts being stamped in each line that interrelate to the parts being stamped so that parts from a first line can be matched by the bench marks to the parts from a second line for optimizing quality of the assembly of parts coming from different press lines.
These and other features, object and advantages of this invention will become more apparent from the drawings and the following written matter: